Some heat exchangers include at least one heat transfer plate having a first surface which is to be thermally contacted with a heat transfer fluid, and an opposed second surface which is to be thermally contacted with an object to be heated or cooled. In such a heat exchanger, heat is transferred through the heat transfer plate between the object to be heated or cooled and the heat transfer fluid.
Providing the heat transfer plate with a high degree of flatness along one or both of its first and second surfaces may be important for a number of reasons. For example, a flat second surface minimizes gaps between the heat transfer plate and the object to be heated or cooled, thereby enhancing thermal contact with the object to be cooled, and maximizing heat transfer. Flatness of the first surface may be desirable to allow the heat transfer plate to bond to an adjacent plate, for example through a brazed or welded joint, to form a circulation channel for the heat transfer fluid along the first surface of the heat transfer plate.
In some applications the second surface of the heat transfer plate may be required to have a surface pattern, for example to enhance contact with the object to be heated or cooled. However, the inventors have discovered that it is difficult to provide an adequate degree of flatness in the above-mentioned heat transfer plates. As a result, the above objectives may not be met on a consistent basis, leading to an excessively high failure rate and/or non-optimal performance of the heat exchanger.
There remains a need for an improved heat exchanger construction and manufacturing method which will ensure adequate flatness of the heat transfer plates.